[speedrider]

I sanded it so I can read it and the number stamped is 52954. The last 4 numbers of my vin are 9791, so I guess this is not the original engine that came with my car. Would that be correct? And thanks for the responses.

[Grand73Am]

Correct. It must not be the original engine to the car.

Are you sure it's a 403?

[speedrider]

Originally Posted by Grand73Am

Correct. It must not be the original engine to the car.

Are you sure it's a 403?

I am definitely sure it's a 403. It has the tell tail oil filler cap just forward of the breather cover. And the 4A heads.

[Grand73Am]

Okay the 4A heads are a clue to the 403. The oil filler isn't, since that's on any Olds engine.
If you get under the engine and look up at the side of the block, there are large 403 numbers cast onto the block, which is the most obvious way to tell .